While drive-through service windows have long been in use by banks, dry-cleaning establishments and fast food restaurants (see such prior art examples as U.S. Pat. Nos. 1,885,560 and 3,702,101), problems in their use have persistently remained. Pull-drawer types require substantial free space, particularly on the indoor side for manipulation of the drawer. Slide-door types, commonly used by fast food restaurants, allow insects to enter the food preparation area as they are manipulated. Frequent use of these windows in peak service periods during cold weather results in substantial thermal loss. In very cold periods the person manning the drive-through station must don special clothing and the duty at the station must be rotated among the personnel to prevent chilling and discomfort. Since drive-through service is a rapidly increasing component of modern fast food service volume (of the order of 25% to 40% in some locations); a drive-through service window assembly which avoids these problems becomes a highly valued equipment item in this trade.
The structure of the present invention utilizes a cylindrical housing mounted for rotation on a vertical axis and supported within a frame. The cylinder is divided into two segments by a chordal wall which is, preferrably, transparent (and may be made of bullet-proof glass for banking or late-open liquor store application). Access openings are made in the cylinder sidewall on opposite sides of the chordal wall. An extensible tray is provided in one of the segments, operated by a handle accessible in the other segment. This segmentally divided cylinder provides a maximum of usable product transfer space with a minimum of interior, free space required for operation. Seals are provided to cooperate with the walls of the cylinder so that in any position of the cylindrical housing, the assembly prevents entry of insects or exterior ambient air into the interior of the building. The concept of the present invention thus remedies the primary defects in prior art drive-through service window structures.